1. Field of the Invention
The present invention relates to a holder for a solid immersion lens.
2. Related Background Art
A solid immersion lens (SIL) is known as a lens for enlarging an image of an observation object. This solid immersion lens is a lens of a hemispherical shape or a superhemispherical shape called a Weierstrass sphere, and microscopic lens in the size of about 1 mm-5 mm. When this solid immersion lens is set in close contact with a surface of the observation object, the numerical aperture (NA) and magnification both are increased, so as to enable observation with a high spatial resolution.
One of the known techniques for securely keeping this solid immersion lens in close contact with the observation object is, for example, the one described in Document 1: U.S. Pat. No. 6,621,275. In the semiconductor inspection system described in Document 1, the solid immersion lens is mounted through a solid immersion lens holder in front of an objective lens (i.e., on the observation object side). The solid immersion lens holder has a chamber with a valve at an end portion thereof, and houses the solid immersion lens in the chamber. The pressure inside the chamber is regulated through this valve to move the solid immersion lens in the direction of the optical axis thereof to achieve optical coupling between the observation object and the solid immersion lens.
The outer shape of this solid immersion lens holder is a tapered shape the inner diameter of which decreases from the objective lens side toward the solid immersion lens side, and a light beam from the solid immersion lens passes the interior of the solid immersion lens holder to enter the objective lens.